import type { AttachmentAdapter } from '@assistant-ui/react';
import type { PendingAttachment, CompleteAttachment, Attachment } from '@assistant-ui/react';

function getFileDataURL(file: File): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => resolve(reader.result as string);
    reader.onerror = (error) => reject(error);
    reader.readAsDataURL(file);
  });
}

/**
 * Generic file attachment adapter that accepts any file type.
 * Files are read as base64 data URLs and sent with their original MIME type.
 */
export class SimpleFileAttachmentAdapter implements AttachmentAdapter {
  accept = '*';

  async add(state: { file: File }): Promise<PendingAttachment> {
    return {
      id: state.file.name,
      type: 'file',
      name: state.file.name,
      contentType: state.file.type || 'application/octet-stream',
      file: state.file,
      status: { type: 'requires-action', reason: 'composer-send' },
    };
  }

  async send(attachment: PendingAttachment): Promise<CompleteAttachment> {
    const dataUrl = await getFileDataURL(attachment.file);
    const data = dataUrl.split(';base64,')[1];
    return {
      ...attachment,
      status: { type: 'complete' },
      content: [
        {
          type: 'file' as const,
          data,
          mimeType: attachment.contentType || 'application/octet-stream',
        },
      ],
    };
  }

  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  async remove(_a: Attachment): Promise<void> {}
}